Rendering and Performance

The defaults suit most apps. This page explains what each one does, so you know when to change it.

GPU rasterization (gpu)

SVG filters and masks are fragment-shader work, and they account for most of the cost of a CPU frame. By default the view rasterizes on the GPU instead:

Platform	Backend order for auto
iOS, tvOS, visionOS	Metal
Android	Vulkan, then GL

If no backend can create a context, the view draws on the CPU. If a context is lost at runtime, for example after a driver reset, the view tries to rebuild it. When the rebuild fails, the view emits contextLost and keeps drawing on the CPU.

Use backend="gl" (or vulkan or metal) only to work around a particular driver. Use gpu="false" to force CPU rasterization.

Off-thread drawing (threaded)

The frame is recorded on the UI thread, then drawn on a render thread that every threaded view shares. A heavy SVG therefore does not hold up the rest of the UI.

Shared sources (shareSrc)

Views with the same src share one parsed document, one animation clock and one recording per frame, the same way <img> tags that point at one file do on the web. For example, ten copies of an icon in a list are parsed once and animate in step.

Sharing saves parsing, memory and recording time. It does not save rasterization, because each view still rasterizes into its own surface. Set shareSrc="false" when one copy needs its own animation timeline.

Android surface type (surfaceType)

Value	Behaviour
texture (default)	Behaves like any other view: it can be transformed, clipped, animated and overlapped.
surface	Composites faster, but cannot be transformed or overlapped. Use it for large, static, full-screen content.

Only visible changes redraw

Animations and DOM mutations trigger a redraw only when the rendered result changes. Several DOM mutations made in the same frame are coalesced into a single redraw.